Conventionally, portable power tools are commonly used in jobs like home improvement and carpenter works. Thus, their designs are generally function-oriented with higher torque and higher rotation speed in mind. However, for achieving higher torque and higher rotation speed, the inevitable consequence may be the heavier and bulkier body structure and ease to produce sharp noise in operation. Not to mention that the manufacturing cost of such high-torque high-speed power tools may be increased. In short, despite the design of a conventional portable power tool is always very function-oriented, it may be still not appearing to users since it can be too pricey and too bulky.
In addition, generally the aforesaid portable power tools are not user friendly especially in a condition when it is not being used. It is noted that users usually stores their unused portable power tools in their tool cabinets or tool boxes, and since such portable power tools are generally single-function devices that they are not capable of performing functions they are not designed to do, it is possible for a users to carry a plurality of such portable power tools of different functions in their tool boxes just for responding to the actual needs on site. This will not only cause heavy burden to the users, but also is not convenient in usage.